Many scientists agree that we’re on the cusp of a battery revolution, propelled by the decline of fossil fuels, as well as the rise of electric consumer vehicles. Solid-state batteries are one of the most promising next directions for the technology to take, they say.
One of those scientists is Jeff Sakamoto, an associate professor at the University of Michigan’s mechanical engineering department. His workgroup studies solid-state batteries as the successor and complement to lithium-ion batteries—today’s gold standard, and a battery revolution in their own right.
Sakamoto grew up working on cars, so he’s interested in finding solutions that will help us transition away from the internal combustion engine and fossil fuels that we currently rely on. He also runs Ann Arbor, Michigan-based Zakuro Inc. to help close the gap between his university workgroup’s big ideas and the long process of research and development for real products in the marketplace.
We spoke to Sakamoto to learn more about his battery research and where it’s headed next. The conversation, lightly edited for style and clarity, follows.
Popular Mechanics: Why should we care about batteries?
Jeff Sakamoto: Currently, transportation of people and goods primarily relies on fossil fuels. Electrifying transportation will reduce fossil fuel consumption. However, electrifying powertrains requires high specific energy (Wh/kg) and affordable ($/kWh) electrical energy storage. Batteries are the leading contender to fill this technological need; specifically Li-based batteries that can achieve > ~200 Wh/kg and < ~$80/kWh.
How did your interests lead you to start studying batteries?
I started working on cars as a teenager. I probably still have grease under my fingernails. Don't get me wrong, the internal combustion engine (ICE) is a great technology and was instrumental in advancing civilization in the 20th century. However, as we move into the 21st century and beyond, we need to rely on sustainable and cleaner energy. To answer the question, my passion for studying batteries is motivated by my interest in car technology/mechanics and altruism. By the way, at the University of Michigan and in Ann Arbor, many of the students and young engineers I'm surrounded by have the same motivation. It's a pretty cool feeling.
What do you think is most important for "battery beginners" to know about your research?
First, state-of-the-art Li ion batteries are great and will be the battery tech to enable the transition from ICE to electric powertrain vehicles. Second, there are challenges related to the cathode raw materials or metals used in state-of-the-art Li ion. Lastly, there is an ever-increasing push to lower cost and improve safety. Addressing some of these challenges could be addressed by studying new types of batteries and materials.
How do you separate your academic interests from operating a battery startup?
The battery industry is expected to be a trillion dollar market or more. Naturally, large companies and battery startups are operating in stealth mode to protect their respective techs and secret sauces...However, the mission on campus is to be open and share information to advance science and engineering. Thus, I founded a battery startup company to create an outlet to conduct research that involves sensitive intellectual property. Essentially, it's the aspects related to intellectual property that separates my academic [work] from my battery startup.
What key factors do you think will separate the lithium-ion era from solid state batteries going forward?
If solid-state batteries are commercialized, it's the performance, safety, and perhaps cost that will separate Li ion from solid-state batteries.
Are there any surprising challenges with solid lithium metal batteries?
I personally think that the major challenges were identified early on in the beginning days of earnest solid-state battery research. However, if there were a surprise, and kind of ironically, it's the physical behavior of lithium metal (anode in many solid-state battery designs) and not the behavior of the solid electrolyte that enable solid-state batteries. There were probably < 10 papers on the physical behavior of lithium metal in the 20th century. Because the operation of solid-state lithium metal batteries is fundamentally different from liquid-containing Li ion batteries, we still need to learn more about the physics of lithium metal as the community progresses toward commercialization.
What will safety be like for solid lithium metal versus lithium-ion batteries in electric cars?
The solid electrolytes that would replace the flammable liquid electrolyte in Li ion batteries should dramatically improve safety. As we've seen and read in the news, this safety issue with liquid electrolytes in Li ion hampers the transitions from ICE to EVs [electric vehicles]. However, a typical solid-state battery using lithium metal would use many kilograms of pure lithium metal, which is reactive when exposed to moisture. Is this a matter of trading one safety issue with another? I am not so sure. Just because lithium metal reacts with moisture, it doesn't mean it's more dangerous than Li ion. There is more research that is necessary to understand the safety of solid-state batteries.
How do solid lithium batteries fit into the near future as we fight climate change?
When a battery scientist looks at the periodic table, there's probably an acknowledgement that there really aren't many if any more combinations of elements to make a battery better than a lithium battery for EVs. Beyond Li ion, I personally feel that solid-state lithium batteries are or are approaching the final frontier in battery technologies for EVs. If viable batteries are necessary to enable the transition from ICE to EV powertrains and IF solid-state batteries supplant Li ion, then it's clear what role solid-state batteries will play in fighting climate change.
Is there other battery research you're excited about from elsewhere in the field?
There are two. First, to address this issue related to some of the raw elements used in state-of-the-art Li ion cathodes, elemental sulfur is a potential cheap, abundant, non-toxic alternative. Lithium would be the anode in lithium-sulfur batteries. However, there remain substantial engineering challenges. Second, with all the focus on EV batteries, attention to electrical grid storage is needed. I am excited about grid battery research. The good news here is that weight and size constraints are dramatically lower compared to EV batteries. The challenge then switches to cost, sustainability, further reduced toxicity, and integration.
What do you hope people do after this?
Battery technology is critical in the transition from fossil fuel to electrical energy. Moreover, this transition is really happening if we look at how many EVs are on the road now and will be in the coming decades. This is a "battery moment" in history. As a battery scientist, engineer, and entrepreneur, I can honestly and confidently say that the battery tech, in some shape, form, or chemistry, will deliver.
Caroline Delbert is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about everything. Her favorite topics include nuclear energy, cosmology, math of everyday things, and the philosophy of it all.
